When sway is involved with continuation of rise it is gradually increased e.g. like in the Waltz. When a progresive movement is required the sway involved to support that is the type of swaywhich is maintained but not increased. This sway curves the body e.g. like in the Foxtrot Picture type of choreography not governed by body swing and rise and fall e.g like in the Tango, requires a specific muscular toning to avoid a broken sway!